The paper scrutinizes the definition, the general and the legal characteristics of tax liquidity. It is a very essential question as to whether taxable persons have enough money to fulfill the obligation of taxpaying, secure their abilities to pay taxes in the future. The tax liquidity can be analyzed specially in the field of duties, ordinary and extraordinary taxes of wealth and natural justice. The legislator can regulate different legal institutions to fulfill the requirement of tax liquidity: it can prescribe for example various allowances, the possibility of deduction or it can ensure different possibilities in the field of fairness.